Thursday, December 24, 2009

Those hoping for snow for Christmas are getting their wish.. snowfall has begun over southern MB today, and will likely continue through Friday before tapering off Saturday. The snow today is the initial wave of the storm system being supported by a trough of low pressure moving in from Saskatchewan. This first wave of snow will bring about 2-8 cm of snow to southern MB today before it dissipates later today into this evening. Another round of snow will move in by Christmas morning from the south as the strong winter storm system pushing into Iowa spreads a large area of precipitation northward. This next wave will likely bring another 5-15 cm of snow to southern MB with the highest amounts near the US border. In addition winds will be increasing Friday from the north which will give reduced visibilities in snow and blowing snow resulting in poor travelling conditions for Christmas day. All told, snowfall totals over the next couple of days will range from 10-15 cm in Winnipeg to 25 cm over the southern and western Red River valley. Note that winter storm and blizzard warnings have been posted for parts of North Dakota and Minnesota due to this storm system.

21 comments:

reports into our office show 2 inches at Pembina...3.5 at Grand Forks and around 6 in Fargo. I was going for a lull in activity down here most of the day into the evening then next snow area to reach later tonight into Friday with this heavier and accompanied by some wind. Coord with neighboring NWS offices indicated to hold off on Blizzard headlines now but likely will need some in eastern ND before the event winds. WFO BIS went ahead...but that area will see the better winds. I was thinking another 8 to 12 inches most of my area from this late tonight into Friday night section.

Thanks for the snow reports Dan.. about 1" (2.5 cm) so far here in Winnipeg as of 8 am, with 2-3" to our west. Looks like snowfall is riding up that inverted trof and giving more significant snow further north this morning.. as inverted trofs often do. Tomorrow's looking potentially nasty here if the NAM is right.. with blizzard conditions possible for much of southern MB especially RRV. GEM has consistently been painting the highest snowfall to our south.. we'll see if that changes today.

Geez, wish me luck on those highways today =~. This is going to be a long ride .. At least don't have to contend with wind and blowing snow. Big burst of snow developing in the Winnipeg area now. About 4cm of fresh snow on the ground here in south Winnipeg so far today. It's about time!

Good luck Jewels! Yeah, looks like a good dumping of snow is coming finally with 10-15cm. Why does this always happen a couple days before christmas? It seems to be like a tradition. Anyways just wanted to mention that, wishing everyone a very merry christams and happy new year 2010.

The NWS is calling for 12 to 14 additional inches of snow along the border. Dan - GF...if you are still around...do you have an idea of what your models are showing north of the border? Does that 12 to 14 inch zone extend to Steinbach...what zone would Winnipeg be in?

The NAM and GFS are in good agreement over snowfall amounts at this point. They both show about 20 to 30cm for south-eastern Manitoba on Christmas and Boxing Day. The GEM shows about 20 to 30cm along the border, with 20cm around Steinbach and around 15cm for Winnipeg. The Ensemble gives a greater than 70% chance of more than 15cm for areas south of the trans-canada.

I'm getting increasingly concerned about tomorrow for much of the RRV and SE MB, including Winnipeg. Most models agree snow of at least 10-20 cm moving into southern MB with this next wave tomorrow, with increasing northerly winds. That will mean snow and blowing snow with blizzard conditions possible especially in the RRV through Christmas Day into Saturday. Even if we don't get that much snow, the increasing winds will blow and drift what snow is falling, and has fallen.. The only problem for a true blizzard may be that winds may not be as strong as they could be due to warmer air aloft, which may prevent getting the stronger winds to surface. Still, should be enough wind to casue problems.. We'll see what happens.. but it's not looking like a good day for travel tomorrow..

Narrow mesoscale bands set up with this initial shot of warm advection. Energy did not consolidate fast enough to our south keeping the pipeline of moisture alive. Precip finally lifting north and eventually will weaken as lead disturbance loses definition. Inverted troughs certainly do have reputation for giving higher snow totals than expected as mentioned, but I have also witnessed inverted troughs wash out as they move east into Manitoba in similar scenarios so its a tricky proposition predicting these guys.

GFS is now somewhat further NW with the deformation zone... showing around 9 mm water equivalent for us. Snow backs into the Winnipeg area by mid morning tomorrow. Snow ratios are a bit tricky because a layer of warm drier air at 850 hPa is projected to dumbbell all the way around the upper low. 850 temps of -4 C (although 700 temps at -9 C) eventually move in. Models show -2 at 850 hPa in NW Ontario which would make for sticky almost wet snow. Something to watch for perhaps is how fast this warmer dryer intrusion can shut down precip over us. GFS depicts this this dry wedge affecting us by 12Z Saturday whereas NAM holds it off until 00Z Sunday allowing for more accumulation.

I hope GFS is correct, not looking forward to impassable back lanes, huge snow drifts...not to mention all the possible stranded holiday travelers. Only saving grace is that there is not a dump of arctic air working in behind the system as noted.

6 cm here in Charleswood from round one of storm. Round 2 arrives tomorrow morning and continues through Friday night into Saturday morning with increasing winds. Conditions will be the worst Friday afternoon into Friday night. Models showing another 10-15 cm, possibly 20, on the way for the city before it tapers off Saturday. Things will be worse south of Winnipeg especially towards Emerson with heavier snow, stronger winds and deeper drifts. Won't be much cross border Boxing Day shopping this year!

On our plot of snowcover...there are several stations that appear in southern Manitoba. It looks like Emerson...Gretna and maybe Morden or Carman.... I was just curious if you knew which sites in southern Manitoba report snowdepth in their obs so that it gets into the NWS system. Thanks Dan NWS GFK

Most of EC's weather stations in southern MB are automated, and only a few report snowdepth (with a sonic snow sensor) Only Brandon A still takes manual snowdepths.

Those sites you mention all report snowdepth with a sonic snow sensor. Snowdepth appears in the station synoptic report at 12z, but I'm not sure if NWS gets that info.

You can always go to our online climate archive database for this information, but it's usually a day or 2 old before its updated. Try.. http://www.climate.weatheroffice.ec.gc.ca/advanceSearch/searchHistoricData_e.html

Under "search by proximity" option, select "Winnipeg", within "200 km", and "for a specific date" input a date from 2 or 3 days ago. This will call up all current climate and weather stations within 200 km of Winnipeg, and you can get daily climate data for each station, including snowdepth for those who report it.

EC also has a volunteer climate station bulletin that lists co-op climate data across the Prairies (including snowfall and snowdepth) The header for this bulletin is CSCN22 CWEG, but I don't know if NWS has access to it on their circuit.

Travel not advised over most ND highways, and a few roads over southern MB between Morden and Pilot Mound. I suspect that "travel not advised" list will grow as the day wears on, with possible road closures especially down toward Emerson. Pembina webcam is looking pretty nasty! That being said, I'm surprised vsbys aren't lower across ND this morning.. they have the wind and the falling snow.. yet vsbys are generally above 3/4 mile. Should get worse today I suspect..